12-Month SIM-Only Contracts

12-month SIM-only contracts: when they make sense

A 12-month SIM-only contract locks in your monthly price for a year in exchange for a discount over the rolling rate. The discount is typically 15-30% on equivalent allowances, which adds up to £30-£100 over the year. 12-month deals also tend to bundle the bigger allowances - it is the natural home of unlimited data plans, and the route most shoppers take when sorting by total cost on our cheapest SIM-only deals page. The lock-in matters in two ways: you cannot leave without paying an early termination fee covering the remaining monthly charges, and most UK networks raise prices once a year (in April) tied to inflation. Since 17 January 2025 networks have to disclose the price rise in pounds rather than a CPI percentage at the point of sale, so you can do the maths up front. A 12-month deal makes sense if your usage is stable, if you are happy with the network is coverage, and if you can absorb a mid-contract price rise. If any of those is uncertain, a rolling plan and the freedom to switch usually beats a small monthly saving. 12-month plans are typically only available from the four big networks and a handful of MVNOs (notably iD Mobile and Smarty) - giffgaff, 1pMobile, Spusu and Lebara are rolling-only.